Adjustable centerboard



April 5, 194-9. 6. J. DANKO ADJUSTABLE CENTERBOARD Filed Sept. 13, 1946 INVENTOR. a J. Dankm Eecm ATTORNEY Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE ADJUSTABLE CENTERBOARD George J. Danko, Chevy Chase, Md.

Application September 13, 194.6, Serial No. 696,966

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention relates to improvements in centerboards and more specifically to adjustable centerboards for sailboats.

The primary object of the invention is to provide a centerboard which is easily adjustable longitudinally of the vessel so that the center of lateral resistance thereof may be shifted to the proper position relative to the center of effort. The advantage of this adjustable centerboard relative to the fixed type is that it gives a perfect trime to the vessel at all angles to the wind and under all conditions of load.

Another object of the invention is the provision of a one-piece adjustable centerboard which may be readily built from inexpensive material such as wood or sheet metal.

Other objects and advantages of the invention will become apparent during the course of the following detailed description taken in connection with the accompanying drawing, forming a part of this specification, and in which drawing,

Figure 1, is a fragmentary perspective view of a boat hull equipped with my improved centerboard and centerboard well. Figures 2-5 are central longitudinal, vertical, sectional views of the centerboard well and showing the centerboard in elevated, aft, intermediate and forward positions, respectively.

In the drawing, which for the purpose of illustration shows only a preferred form of the invention, and wherein similar reference characters denote corresponding parts throughout the views, the numeral 10 designates a portion of the hull of a sailboat comprising a keel l I and planking 12 connected by ribs l3. Rigidly mounted on the keel l I and surrounding a longitudinal slot M therein is the centerboard well or casing 15 comprising sidewalls l6, l1, and forward and aft end walls l8, l9.

Vertically disposed in the well I is a pentagonal centerboard 2|] including upper and lower end portions 2|, 22. The lower end portion 22 is of a uniform width substantially equal to the length of the centerboard well l5 and is defined by parallel sides 23, 24 and an oblique lower edge 25. At its upper end portion 2|, the centerboard decreases in width toward its upper extremity. The adjacent forward and aft edges 26, 21 of the upper end portion are disposed in obtuse angular relation respectively to the forward and aft sides 23, 24 of the lower end portions. The corners of the pentagonal centerboard are preferably rounded, as shown. Any suitable material, such as wood or sheet metal may be used. If desired, the centerboard may be weighted as 2 by depositing lead 28, while molten, in an opening 29 at its lower end portion. The edges of the opening 29 may be provided with weight anchoring means, such as nails 30 driven into the sides of the opening before depositing the lead.

Extending through the centerboard near its upper end is a transverse dowel 31 whose opposite end portions upon lowering of the centerboard engage the upper edges of the sidewalls I6, I! of the well. These sidewalls are each provided with a series of half-round notches 32 in aligning pairs for accommodating and releasably holding the opposite end portions of the dowel 3| in any one of a plurality of set positions.

Attached to the centerboard well or casing, as by a cord 33, is a pin 34 extendable, upon elevation of the centerboard as shown in Figure 2, through an. opening 35 in the lower end portion of the centerboard. The arrangement is such that pin 34 will coact with the notched sidewalls I 6, ll of the centerboard well to support the centerboard in its elevated or inoperative position upon extension of the pin through the opening 35, and will likewise coact with the notched sidewalls I6, I! to support the centerboard in a partially lowered operative position, as indicated by broken lines in Figure 2, upon extension of the pin through another opening 36 between the opening 35 and the dowel 3|.

Inasmuch as the centerboard at its lower end portion is of a width substantially equal to the length of the centerboard well, the lower'end portion of the centerboard is restricted to vertical movement in the well. However, upon lowering of the centerboard to the position. shown in Figures 1 and 4, wherein the upper end portion 2| is disposed in the well, the top of the centerboard may be shifted forward or aft as shown in Figures 3 and 5, respectively. When the top of the centerboard is moved forward as shown in. Figure 3, the lower end portion 22 is shifted aft as a result of the sliding and rocking engagement of the obtuse angular portion of the forward edge of the centerboard with the forward end wall N3 of the well. Conversely, when the top of the centerboard is moved aft, the lower end portion 22 is shifted forward due to engagement of the obtuse angular portion of the aft edge of the centerboard with the aft end wall I9.

It is clear that the lower end portion of the centerboard may be releasably held in any one of a plurality of longitudinally adjusted positions by engagement of the dowel 3| with selected notches 32 in the sidewalls of the well so that the center of lateral resistance of the boat will correspond with the center of efiort or pressure of the sails. Also it will be noted that the centerboard may be longitudinally shifted without substantial change in the efiective area of the centerboard.

Various changes may be made in the form of invention herein shown and described without departing from the spirit of the invention or the scope of the following claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In a boat, a casing forming an elongate centerboard well, a. centerboard having a lower end portion and an upper end portion, the lower end portion being of substantially uniform width and the upper end portion decreasing in width toward its upper extremity so that the centerboard may be rocked in the direction of thellength of the centerboard well upon disposition of its upper end portion in the casing, and a pin extending transversely of the upper end portion of the centerboard for supporting the centerboard in the easing, the upper portion of the casing being provided with a series of notches each for releasably holding the pin in one of a plurality of positions of the centerboard, the lower end portion of the centerboard being provided with an opening for receiving a pin cooperable with one notch of said series to support the centerboard in an elevated position in said well.

2. In a boat, a casing forming an elongate centerboard well, a centerboard having a lower end portion and an upper end portion, the lower end portion being of a substantially uniform width slightly less than the effective length of the centerboard well whereby the walls of the casing restrict the lower end portion of the centerboard to vertical movement in the well, the upper end portion of the centerboard decreasing in width toward its upper extremity whereby the centerboard, upon disposition of its upper end portion in the casing, may be rocked in the direction of the length of the centerboard well for longitudinal adjustment of the lower end portion of the centerboard below the well, and means fixing the centerboard in any one of a plurality of positions relative to the casing.

3. In a boat, a casing forming an elongate centerboard well, a centerboard having a lower end portion and an upper end portion, the lower end portion being of a substantially uniform width 4 slightly less than the effective length of the centerboard well whereby the walls of the casing restrict the lower end portion of the centerboard to vertical movement in the well, the forward and aft edges of the upper portion being disposed in obtuse angular relation respectively to the forward and aft edges of the lower portion whereby the upper end portion of the centerboard decreases in width toward its upper extremity so that the centerboard, upon disposition of its upper end portion in the casing, may be rocked in the direction of the length of the centerboard well for longitudinal adjustment of the lower end portion of the centerboard below the well, and means fixing the centerboard in any one of a plurality of longitudlnally adjusted positions relative to the casing. 4. In a boat, a casing forming an elongate centerboard well, a centerboard having a lower end portion and an upper end portion, the lower end portion being of a substantially uniform width slightly less than the effective length of the centerboard well whereby the walls of the casing restrict the lower end portion of the centerboard to vertical movement into and out of the well, means fixing the centerboard in any one of a plurality of vertically adjusted positions including a pin extending through one of a series of transverse openings between the upper and lower ends of the centerboard and supported by the casing, the upper end portion of the centerboard decreasing in width toward its upper extremity whereby the centerboard, upon disposition of its upper end portion in the casing, may be rocked in the direction of the length of the centerboard well for longitudinal adjustment of the lower end portion of the centerboard below the well, and means fixing the centerboard in any one of a plurality of positions longitudinally of the casing including a pin extending through the upper opening of said series of openings and a series of pin-receivin notches along the top of the casing between the forward and aft ends of the centerboard well.

GEORGE J. DANKO.

REFERENCES CITED UNITED STATES PATENTS Name Date Pigott May 23, 1893 FOREIGN PATENTS Country Date Great Britain (1896) Jan. 1, 1897 Number Number 

